Print hammer control means in high speed printers



United States Patent [72] inventors Matthew J. Costello Larchmont, New York; Frank J. Ziron, 3rd, Stratford; Henry Bleggi, Fairiield; Allen C. Berg, Wilton, Connecticut [21] Appl. No. 755,619 [22] Filed Aug. 27, 1968 [45] Patented Dec. 8, 1970 [73] Assignee Sperry Rand Corporation New York, New York a corporation of Delaware [54] PRINT HAMMER CONTROL MEANS IN HIGH SPEED PRINTERS 10 Claims, 4 Drawing Figs.

[52] 11.8. C1 101/93 [51] Int. Cl. B4lj l/34, B4 1 j 9/36 [50] FieldofSearch 101/93; 340/1725 [56] References Cited UNITED STATES PATENTS 2,627,807 2/1953 Buhler 101/93 2,776,618 1/1957 Hartley 101/93 2,906,200 9/1959 Pfleger 101/93 2,910,935 11/1959 Gignetti 101/93 3,001,469 9/1961 Davis etal.. 101/93 3,117,514 1/1964 Doersam 101/93 Primary Examiner-William B. Penn Attorneys-Marshall M. Truex, Thomas P. Murphy and H.

Walter Clum ABSTRACT: A high speed printer for printing output data of an electronic desk calculator or similar device. A print wheel having type characters arranged in a plurality of columns forming rows of like characters is continuously rotated in synchronism with a toothed shaft. A like plurality of print initiating latch, mechanisms each having a print hammer are disposed about the shaft to permit one or more latch mechanisms to engage a selected tooth to cause its associated hammer to strike a character in a selected row. Each like character is printed on a print line simultaneously and all characters to be printed are printed during one revolution of the print wheel. The output data to be printed is inserted unit by unit in a register of the calculator and each unit is compared with the encoded next upcoming print wheel character. For each true comparison a solenoid associated with a particular latch mechanism is energized to cause simultaneous print: ing of like characters on a line. For the next upcoming character on the print wheel the data units which compare to that character are simultaneously printed in their places on the print line. This comparison is made for each character on the print wheel so that after one complete revolution of the print wheel all characters of the number have been printed.

The present invention relates to a high speed printer and more particularly to a high speed printer which simultaneously prints all like digits (wherein for present purposes a digit may be letters of the alphabet as well as numbers) of a multiple digit word tobe printed on a line when a print wheel comes into the appropriate print position. For example, when a row of ones on a print wheel comes into print position, all the ones appearing in the multiple digit word are printed. Then, all the two's of the digit word are printed when the print wheel comes into the two print position. This process repeats until all the digits of a numerical word are printed in their respective positions on a line in one revolution of the print wheel.

The printer of the present inventionhas been developed for use with an electronicdesk calculator and is described in connection therewith. However, it will-become apparent that the high speed printer of the present invention may be used with any electronic data processor or like apparatus to print any alphanumeric multiple digit word whose digits may be stored in a temporary storageregister.

i More specifically the present invention contemplates a high speed printer comprising a print wheel having type. characters arranged in columns of increasing value forming rows of type characters of same numerical value. While not described, additional rows of characters may also include letters of the alphabet as well as other symbols or characters. However, for purposes of explanation, the description of the high speed printer of the present invention is limited to printing the numeric results normally provided by an electronic calculator.

The print wheel is rotated in synchronism with a shaft of the snatch bar type. A plurality of latch means equal in number to the number of columns of characters on the print wheel are disposed in operative relationship to the shaft. A print hammer is connected to each latch means so that when one or more latch means are actuated to engage a tooth of the shaft,

. its associated print hammer strikes a character in its respective column and in the row which is in print position at that time.

Electronic circuitry is utilized to compare every digit of the number to be printed with each row number. Eachtime a digit compares or matches the number in the particular row undergoing comparison a comparison signal is provided. In the embodiment described there are l l rows, one for each number from to 9 and a row of decimal points. Thus, the comparisonis repeated 11 times. For each such comparison all digits in the number to be printed for which a comparison signal is generated .are simultaneously printed in their ap- A fixed tube 14 longitudinally encases the shaft 11 which is rotatable therein. The tube 14 has a plurality of arcuate slots 15 formed therein in parallel relationship. At each slot 15a I power action ring 16 is mounted for rotation on the tube 14.

propriate positions in the print line. Each comparison signal energizes a solenoid means which trip the latch means to actu ate the required print hammers. The comparison with all the digits in the number to be printed is again made with the next upcoming number row on the print wheel and all digits generating a comparison signal-for that number are simultaneously printed. This is repeated through one revolution of the print wheel until all digits of the number have been printed. The structural details of the invention will become more ap parent from the following description taken in conjunction with the attached drawings wherein:

FIG. 1 is a perspective view 'of the print action mechanism of the present invention;

Each poweraction ring 16 comprises a sleeve portion 17. The sleeve has an arcuated opening 18 for registration with its respective slot 15 in the tube 14. The sleeve portions 17 in addition to providing support for their respective power action rings 16 act as spacers when all the power rings are in position on the tube 14. I

Each power action ring 16 includes a flange 19 formed integrally therewith. As seen in FIGS. 1 and 2 the flange 19 has a radially extending fin 20 on which is mounted a latching mechanism 21 to be described more fully below. The fin 20 has formed therein an eye tab 22 which has one end of a tensionspring .23 connected thereto. The other end of the tension spring is connected to fixed means, not shown. The tension spring 23 yieldably maintains the power action ring 16 at a home position holding the eye tab 22 in abutting relationship 'to stop 24.

A link 25 has one end pivotably connected to the fin 20 by a stud 26. The other end of the link 25 is connected to one end of a print hammer arm 27. The other end of print hammer arm 27 has formed thereon a print head 28. The print hammer arm 27 abuts a stop 29 when in the rest position as shown.

The print hammer arm 27 is mounted for free rotation on a shaft 30. Asseen in FIG. 1 each printhammer arm 27 is mounted on the shaft 30 with each" being freely and individually rotatable thereon.

Thus, when oneof the poweraction rings 16 is caused (by means to be described) to rotate clockwise on the tube 14 its associated link 25 causes its print hammer arm 27 to rotate clockwise about the shaft 30 without affecting the print hammerarms 27 of the unactuated power actionrings 16.

The latching mechanism 21 comprises a pawl carrier 31 which is pivotably mounted on the fin 20 by means of the stud 26. The pawl carrier 31 has a de'tent shoulder 32 formed thereon. The pawl carrier 31 also has a forked end comprising spaced prongs 33 and 34. A pawl 35 is pivotably mounted on the pawl carrier 31 as at 36. A stud 37 is secured near one end of the pawl 35. Spring means 38 yieldably maintains the pawl 35 in the position shown with thestud 37 abutting the prong 33. The spring means 38 also biases the pawl carrier 31 clockwise about the stud 26.

When the latching mechanism'21 is in the unactivated con dition, as shown, the pawl tooth 39slightly extends through the arcuate opening 18 of the power action ring 16 and also through the coinciding slot 15 in the: tube 14. When in the actuated condition, the pawl tooth 39 is extended to be engaged by a tooth 13 ofthe shaft 11.

The means for activating the latching mechanism 21 comprises a trigger 40 pivotably mounted on the fin 20 at pivot 36. The trigger 40 includes a lip 41 normally engaging the shoulder 32 to hold the pawl carrier in the latched or unactivated condition against the bias of spring means 38. The

, trigger'40 alsoincludes a trigger arm 42. Clockwise rotation of FIG. 2 is a side elevation view of the high speed printer of the present invention;

FIG. 3 illustrates the type character arrangement of the print wheel of the present invention; and

FIG. 4 shows in block diagram form the comparison circuit used in the present invention.

Referring now to FIGS. .1 and 2there is shown in perspective a portion of the print action mechanism 10 of the present invention. The print action mechanism 10 comprises a shaft 11 having a plurality of longitudinal spline ways 12 forming teeth 13. Such a shaft is commonly referred to as a snatch bar. In a practical embodiment the shaftll has six teeth or onehalf the number of character spaces in a column of the print the trigger 40 about the pivot 36 removes the lip 41 from engagement with theshoulder 32. Thespring means 38 then causes the pawl carrier 31 to pivot clockwise on the stud 26 bringing the pawl tooth 39 into the path of the next oncoming tooth 13 of the shaft 11. This causes the tooth 13 to engage the pawl tooth 39 to thereby rotate the power action ring 16 on the tube 14 to cause the print hammer arm 27 to strike a print 1 wheel to be explained more fully below.

After the power action ring 16 rotates a predetermined angular distance'on the tube 14,'the.trigger 40 is relatched by causing its lip 41 to reengage shoulder 32. When the trigger 40 relatches the pawl carrier 31, the spring 33 returns the power action ring 16 to its home position which is the position shown in the drawings.

Restoration of the trigger 40 to the latched condition is caused by the camming out of the pawl tooth 39 when its edge 43 meets the edge44 of a slot 15 'of the tube 14 in the rotation of thepower action ring 16 about the tube.

During interaction with a shaft tooth 13, the pawl 35 may rotate counterclockwise about the pivot 36 against the bias of the spring means 38. This assures full bite of pawl tooth 39 with shaft tooth 13.

As aforesaid there is a power action ring 16 for each slot 15 and each one may be actuated independently of the others so that one or two or more may be actuated simultaneously to simultaneously activate more than one of the print hammers arms 27.

Each trigger 40 has operably associated therewith a solenoid 45 which when energized causes its armature 46 to move counterclockwise. A spring 47 assures return of the armature to its unactuated position when the solenoid 45 is unenergized. The stops 48and 49 act as limits to the armature 46.

The high speed printer of the present invention comprises a print wheel 50. The print wheel 50 is mounted for rotation on a shaft 51 and in operation is synchronously rotated through a gear or similar arrangement (not shown) with the shaft 11. Embossed or otherwise formed or fixed on the print wheel 50 are type characters arranged in columns of ascending numerical value i.e. -9 forming rows of like numbers.

As best seen in FIG. 3, the print wheel 50 comprises around its periphery equally spaced rows of numbers eg a row of 0's, a row of 1's. A row of decimal points or other characters may be included. The rows of like numbers forms a plurality of columns columns are shown but there may be more or less depending on the number of digits desired to be printed on the print line).

The distance separating the row of decimal points and Os is twice that separating other adjacent rows for reasons which will become apparent later on in this description.

As shown in FIGS. 1 and 2, the print wheel 50 is so disposed with the rest of the printer that a print hammer arm 27 is alined with a column of number type of the print wheel 51. Thus, whenever a print hammer arm 27 is actuated through its print action ring 16, a print head 28 will strike a number in its respective column on the print wheel 50. Synchronization of print wheel 50 and shaft 11, assures a square hit on a type number by the print head 28, whenever a print hammer arm 27 is actuated. Since the shaft 11 has six teeth and the print wheel has 12 rows (one empty),-the shaft 1-1 is rotated at twice the speed of the print wheel 50. This is accomplished by any suitable gearing (not shown). Then the print wheel 50 is initially adjusted .on its shaft 51 by means of set screws 52 to a position at which each print head 28 upon actuation will squarely strike a number on the print wheel 50. Thereafter, a row of numbers is always in print position when an actuated print head reaches the end of its swing.

As best seen in FIG. v1 each print hammer arm 27 is provided with a print impression'control spring 53 disposed in the path of a protrusion 54 formed on the print hammer arm 28. Thus, when the print hammer arm 27 is near the completion of its swing, the protrusion 54 interacts with spring 53 which ab sorbs most of its energy thereby decreasing the force with which the print head 28 strikes a number. An adjustment screw 55 is provided for varying the force (and the noise) with which the print head 28 is permitted to strike a number. The impression control spring 53 also aids in returning the print hammer arm 27 to its rest position.

A web of print paper 69 is disposed between the print wheel and the print heads 28 and may be transported in any conlar solenoid 45 which is energized depends on the position within the number to be printed of the digit which compares with the print wheel number. Thus, if the number to be printed is 111665544332211, then the first, second, 13th, 14th and 15th solenoids will be energized from right to left, as shown in FIG. 4. When the number on the print wheel next coming into position is two, all the digits of the number to be printed are compared with it. All 2s of the number to be printed will produce a match and the appropriate solenoids are energized. In the case of the example number, the third and fourth solenoids from the right would be energized. This comparison continues for each number of the print wheel row that is next coming into print position until after the print wheel has made one complete revolution the comparison is complete.

Referring now more particularly to FIG. 4 block 56 represents a calculator. In an actual embodiment calculator 56 is an electronic desk calculator of the type utilizing a recirculating loop memory of the delay line type. However, any electronic data processing apparatus or similar device capable of presenting output data to be printed in the form of encoded digits to an output register may be used in the present invention.

The calculator 56 being of the recirculating loop memory type manipulates data serially. In a practical embodiment the data is in binary coded decimal form. In other words each word comprises a plurality of digits wherein each digit is represented by a four bit binary number. The register 57 which is connected to the calculator 56 is a four bit shift register and normally forms part of the recirculating loop memory of the calculator 56.

When the calculator 56 completes an arithmetic operation and contains data to be printed out, each digit of a number to be printed is temporarily stored in the register 57. This may be accomplished by removing the register 57 from the recirculating memory by disconnecting the path or line 58. At the same time line 59 is inserted in the recirculating line. Thus, any digit in the register 57 is statically stored there until the register 57 is inserted back into the recirculating line. In the art this process is commonly called right shifting. During the time that the register 57 is out of the line and storing a digit the recirculating path comprises the line 59 and the calculator 56. If the number to be printed comprises 15 digits (it may be more or less depending on the capacity of the calculator), the least significant digit LSD is permitted to enter the register 57. Then, the register 57 is disconnected from the line to store the LSD of the number to be printed. After one complete circulation of data through the line 59 and thecalculator 56, the register 57 is again made part of the recirculating line long enough to receive the next LSD which is stored therein for one circulation. This is repeated for each digit of the number to be printed and the whole process is continuously repeated while the calculator 56 is in the printout mode.

For purposes of this invention, however, it is necessary only that the number to be printed be stored in a register similar to register 57 so that all .the digits of the number may be compared with each number on the print wheel. Since the print wheel 50 has 10 numbers and a decimal point thereon, the comparison is repeated 1 1 times.

The register 57 is connected to a comparator 60.

The print wheel 50 has an aperture 61 extending longitudinally through it adjacent each row of characters substantially as shown in FIG. 4. It should be noted that FIG. 4 shows the print wheel 50 as being one column wide whereas in reality it is 15 columns (or more) wide.

A light source 62 and photocell 63 are positioned so that as the print wheel 50 rotates a pulse of light may pass through an aperture and strike the photocell 63 as each row of numbers passes by.

The photo cell provides an electrical pulse to a delay flop 64 in response to each light pulse. The delay flop may be of any conventional type. V

The delay flop 64 in response to each pulse from the photo cell provides a pulse to a counter 65 of the well-known binary type. In response to each pulse from the delay flop 64 the counter 65 is incremented by one. If the delay flop does not receive a pulse from the photocell within a predetermined time, it provides a reset pulse to the counter 65 resetting the counter 65. Alternately, the counter 65 may be automatically resettable when a predetermined time elapses between pulses from the delay flop 64.

As is shown in FIG. 4 the distance on the print wheel 50 between the row of decimal'points and the row .of 's is twice as long as between any other pair of adjacent number rows. For a given rotational speed of the print wheel, it can be seen that the parameters of the delay flop 64 may be chosen the cause it to reset the counter 65 somewhat before the aperture associated with the row of 0s passes between the light source 62 and the photocell 63. In an actual embodiment of the present invention the rotational speed of the print wheel 50 is such that the timeinterval for adjacent rows of numbers to pass a fixed point is 14 ms. with the exception that the time lapse for the decimal point row and the 0 row to pass the fixed point is twice as long or 2 8'ms. The lack of a pulse from the photocell 63 within l4 ms..of its last pulse is the condition for which the counter 65 is reset.

Thus, the counter 65 is reset each time the print wheel 50 makes a completerevolution. When the counter 65 receives a the first pulse after being reset, it stores a 0 in binary or any other desired code e.g. the excess three code. With the second pulse the counter 65 registers a land so on up to the decimal point (which may be encoded as a 10) after which it is reset.

The counter 65 in practice is conventional and may comprise four flip-flops which effectively translates or encodes each row number into a binary (or other desired code) digit. Each flip-flop has an output terminal so that the combination of highs and lows (1's and 0's) on the four output terminals gives the encoded number. However, the counter 65 is shown connected to the comparator via a single conductor..

The comparator 60 provides anoutput signal each time a digit in the register 57 matches a digit in the counter 65.

The comparator 60 is connected to print signal generator 66 which provides a print signal to a scanner 67 each time there is a match. r

The print signal generator 66 may, if desired, be enabled i only when'the calculator is in the printout mode and providing a print mode signal PR to the'print signal generator. In addition a right shift signal RSH provided when the calculator 56 is in the right shift condition i.e. the register 57 being disconnected from the memory loop, may also be necessary to enable the print signal generator.

The print signal is applied to the scanner 67. The scanner 67 may comprisea plurality of AND gates (not shown). In the embodiment being' described there are 15 AND gates since there are 15 possible digits in a number to be printed. The input of each AND gate is connected to the print signal generator 66. The output of each AND gate is connected to a respective solenoid 45.

A shift counter 68 is connected to the scanner 67. In the embodiment being described, the shift counter 68 may be a binarycounter capable of counting at least to 15. Thus, it may comprise four flip-flops. The output terminals of each of the flipflops are connected as input terminals of each AND gate in the scanner 67. Thus, each AND gate has five possible inputs. Each AND gate is gated on by a different combination of high s and low's if that combination occurs in coincidence with the print signal.

The shift counter 68 is incremented by one each time a new digit is inserted into the'register 57 and resets automatically after it counts 15. Any convenient means maybe used to so increment the shift counter 68 e.g.a clock pulse source used in timing the calculator or the right shift pulse RSH used to disconnect the register 57 from the calculator 56.

When the shift counter 68 registers a count of one and there is a print signal, the first solenoid is energized i.e. the right most one shown in FIG. 4. Thismeans that there is a least significant digit to be printed. When the shift counter 68 registers a count of 2 and there is a print signal the next solenoid is energized to enable printing of the next LSD. It should be remembered there will only be a print signal when thenumber in a row compares with a number in the register 57, The scanner 67 and the shift counter 68 assure that each number is printed in its proper place on the print line.

In operation consider the number 1 1 0 0 2 2 3 4 5 6 7 8 9 l -O as the number to be printed. For the condition where the 5 row of 0s of print wheel 50 is nextcoming into print position the aperture 61 associated with that row has passed between the light source 62 and the photocell 63. Therefore, the digit 0 is registered in the counter 65 in coded form. Now each digit of the number to be printed is stored in sequence in the register 57. The first or LSD is a 0 and there is a match so a print signal is applied to the scanner 67. Shift counter 68 is at the count 1. Therefore, the right most solenoid 45 in FIG. 4 is energized. This releases the associated latching mechanism 21 so that the pawl 35 moves into the path of the next oncoming tooth 13 of the shaft 11. For the next 10 digits of the number to be printed there is no match and therefore no print signals are provided.

The 12th digit is a 0. Therefore there is a match. Since the shift counter is then at a count of l2,'the 12th solenoid from the right is energized and its associated latching mechanism 21 places its pawl 35 into the path of the same tooth 13.

This occurs for the 13th digit which is also a 0. For the 14th and 15th digits there is no match. In a practical embodiment the foregoing occurs in less than half the time required for adjacent teeth 13 to come into the actuation position or less than 7 .ms. since there is a time interval of 14 ms. between each tooth 13 of shaft 11 arriving at pawl actuation position. Therefore, all the pawls 35 placed in the path of the next oncoming tooth 13 are engaged simultaneously and through their respective power action rings 16 actuate respective ones of the print hammer arms 27 to cause tobe printed simultaneously all the 0s in the number to be printed.

The print wheel 50 continues to rotate and when the row of ls has passed light source 62, the number 1 is encoded in the counter 65. This number is then compared with all the digits in the number to be printed in the same manner as above described and all the 1s are printed simultaneously. This occurs for each number row on the print wheel until after the decimal point row has passed the light source 62, the counter 65 is reset to await the next number to be printed. The pulse which resets the counter 65 may also be used to cause the print paper 69 to be advanced to await the next printing.

We claim:

1. A high speed printer for printing output data from a data processing device: 1 p I a rotating print wheel having type characters arranged in 1 columns of unlike characters forming rows of like characters; translating means electrically coupled to said print wheel converting each row character into a coded signal when the row passes a predetermined point; register means connected to the data processing device for sequentially storing during the time that each coded signal is in said translating means each unit of data to be printed;

comparison means connected to said translating means and said a register means providing a comparison signal for each entry is said register means which matches the coded signal in said translating means; and

a print'action. mechanism having print hammer means for each of said columns of type characters: 1 said print actionmechanism including electromechanical means coupled to said comparison for sequentially moving respective print hammer means to a ready position in response to the comparison signals caused by the matches between said units of data to be printed as cycled through said register means and the coded signal in said translating means; and said print action mechanism including mechanical means for causing said print hammer means in the ready position to strike simultaneously respective type characters in the row whose coded signal in in said translating means, whereby. when the print wheel has completed one revolution each row character has in turn been compared with all the units of data of the data to be printed.

2. A high speed printer according to claim 1 wherein said translating means comprises:

detector means disposed adjacent said print wheel providing a signal each time a row of characters passes a predetermined point;

counter means connected to said detector means encoding each row character into a coded signal; and

means for automatically resetting said counter means a predetermined time after the last type character on said print wheel passes said predetermined point.

3. A high speed printer according to claim 2 wherein the distance on said print wheel between the first and last rows of type characters is substantially twice that between the other adjacent rows, said means for resetting said counter means comprising delay flop means providing a reset pulse to said counter means before the first row of type characters passes said detector means.

4. A high speed printer according to claim 1 wherein said mechanical means comprises;

shaft means rotating in synchronism with said print wheel having a plurality of teeth;

a latch means for each column of type characters coupled to said shaft means and a respective one of said print hammers operable when actuated to engage one of said teeth to cause a respective print hammer to strike said print wheel; and

latch actuation means operably associated with each of said latch means and connected to said comparison means to actuate one or more of said latch means dependent upon which of the units of data in said register means matches the coded signal in said translating means.

5. A high speed printer according to claim 4 wherein said shaft means comprises:

a shaft having a plurality of spline ways forming teeth; and

a fixed elongated tube encasing said shaft and supporting each of said latch means, said tube having a plurality of arcuate slots through which respective actuated ones of said latch means engage theteeth of said shaft.

6. A high speed printer according to claim 5 wherein each of said latch means comprises:

a ring mounted for turning movement on said tube and connected to a respective one of said print hammers;

pawl means disposed on each ring to move into and out of engagement with the teeth of said shaft through a respective one of said slots;

resettable trigger means normally holding said pawl means out of engagement with the teeth of said shaft for releasing said pawl means into engagement with a tooth of said shaft;

said latch actuation means disposed to actuate said trigger means for rotating said ring on said tube to drive its respective print hammer; and

means restoring said ring to a home position and resetting said trigger means after said ring has rotated a predetermined distance on said tube.

'7. A high speed printer according to claim 6 wherein said latch actuation means comprises a solenoid for each of said trigger means connected to said comparison means for energization by respective comparison signals.

8. A high speed printer according to claim 7 wherein said encoder means comprises:

detector means disposed adjacent said print wheel providing a signal each time a row of characters passes a predetermined point;

counter means connected to said detector means encoding each row character into a coded signal; and

means for automatically resetting said counter means a predetermined time after the last type character on said print wheel passes said predetermined oint. 9. A high speed printer according to c aim 8 wherein the distance on said print wheel between the first and last rows of type characters in substantially twice that between the other adjacent rows, said means for resetting said counter means comprising delay flop means providing a reset pulse to said counter means before the first row of type characters passes said detector means.

10. A high speed printer according to claim 6 further including energy storage means disposed inthe path of each of said print hammers for controlling the force with which said print hammers strike said print wheel, said energy storage means also aiding in returning said print hammers to their rest positions. 

